1. Field of the Invention
The present invention relates to a copier, printer, facsimile apparatus or similar image forming apparatus and a toner collecting device arranged in an image forming unit included in the image forming apparatus and more particularly to a toner collecting device including toner conveying means for conveying collected waste toner to a waste toner storing portion.
2. Description of the Background Art
It is a common practice with a copier, printer, facsimile apparatus or similar image forming apparatus to uniformly charge the surface of an image carrier implemented as a photoconductive body, expose the charged surface of the image carrier imagewise to form a latent image, deposit toner or similar fine particles on the latent image with a developing unit for forming a corresponding toner image, transfer the toner image from the image carrier to a recording medium either directly or via an intermediate image transfer body, and then fix the toner image on the recording medium for thereby producing a print. The prerequisite with such an image forming apparatus is to remove toner left on the image carrier without being transferred to the recording medium due to the potential distribution balance, fog or forced stop of the apparatus to thereby clean the surface of the image carrier.
Modern image forming apparatuses include one of the type including a mechanism for collecting the toner removed from the surface of the image carrier (referred to as waste toner hereinafter) and storing it in, e.g., a collecting portion included in an image forming unit or returning it to a developing device for reuse.
Japanese Patent No. 3,281,595, for example, discloses an electrophotographic recording apparatus including a toner conveying belt mounted on one side of a process cartridge and configured to convey toner collected from the surface of a photoconductive drum to a developing section via a toner collecting chamber. This document describes in paragraph [0016] that the toner conveying belt is driven by a pulley which is also mounted on one side of the process cartridge, as shown in FIG. 1 of Japanese Patent No. 3,281,595.
In the above paragraph [0016] of the same document, there is simply described that the pulley is rotated by a drive source, not shown, in a direction indicated by an arrow. However, it has been customary with an image forming apparatus to arranged a driveline for driving a photoconductive drum or the like (referred to as a body driveline hereinafter) at one side of the apparatus body and arrange a toner conveying belt or a toner conveying screw and so forth for the collection of waste toner at the other side (referred to as a counter drive side hereinafter) and drive it by driving a pulley or a gear, which is mounted on one side of a process cartridge or an image forming unit, with a shaft extending from the body driveline. Such a configuration facilitates the layout of the toner conveying belt or the toner conveying screw and pulleys and gears for driving it.
However, a gear train or similar drive transmission mechanism arranged at the counter drive side for driving a toner conveying belt or the toner conveying screw is undesirable because it increase the number of parts, increases the number of assembling steps while sophisticating the assembly, causes drive transmission losses to accumulate, and increase required torque and therefore aggravates power consumption, thereby increasing the overall cost of the apparatus. Moreover, because the gear train, for example, needs an exclusive space at the counter drive side, the width of the process cartridge or that of the image forming unit and therefore the overall size of the apparatus increases.